In an open letter to the Chinese government, Jiang exposed efforts to cover up the SARS epidemic and helped prevent the global epidemic from spiraling further out of control.

His act of conscience sounded the alarm and forced Chinese health officials to pull out all stops to ultimately halt the spread of the virus that would claim almost 800 lives worldwide, over 300 of them in China.

Challenges to China's official line from within rarely go unpunished. Indeed, patriotism in China is largely seen as a show of loyalty to the nation's leaders.

But it seemed Jiang was forgiven because he was deemed to be working for the people.

Then in February, Jiang touched an even more sensitive nerve.

He sent a letter to around 20 senior Chinese lawyers asking the Communist Party -- of which Jiang is a veteran member -- to admit the 1989 Tiananmen Square crackdown was a mistake.

The letter, which was leaked to Chinese and international media, sent shock waves throughout the Communist Party.

Jiang described his recollections of the scene at the hospital he was working at on the night the People's Liberation Army opened fire on pro-democracy demonstrators in a bid to end the protest.

China's official line is that the Tiananmen protests was a "counterrevolutionary rebellion" and denies killing hundreds of innocents.

"His letter was powerful," says human rights activist Hu Jia.

"He has so much credibility. He was a doctor in 1989 and saw 80 people who died. When he spoke out, the government could no longer deny what happened."

Last month, on his way to the U.S. Embassy to get a visa to visit his California-based daughter, Jiang and his wife were arrested.

"They're trying to use the detention to pressure him to admit what he did was wrong, especially the letter he wrote this year regarding the Tiananmen massacre," says daughter Jiang Rui.

After his daughter spoke to CNN on June 15, Jiang's wife was released.

But those close to the family say the government told her and her children not to talk to the media.

Human rights activist Hu says he spoke with Jiang's wife by phone.

Hu told me she spoke in guarded tones and left the impression there were security officers in her apartment.

What is clear is that however open and modern China appears, the Communist Party is still determined to silence those who challenge its authority.